Most semiautomatic handguns include a frame and a slide that moves along the firearm's longitudinal firing axis in a reciprocating manner. The frame provides the core support structure for the firearm's operational and other components, e.g., trigger and firing mechanisms, grip, ammunition feeding system, barrel, and slide. For operably attaching the slide to the frame, the frame includes a set of rails positioned on opposite longitudinal sides of the frame. The rails are integral with the rest of the frame, i.e., the frame, including the rails, is machined or otherwise formed from a single piece of metal or other material.
In addition to the rails, the frame includes other integrally machined features for attaching, supporting, and/or guiding additional components of the firearm such as the trigger and firing mechanism sear. While such features (including the rails) function well from an operational standpoint, the manufacturing process for forming the rails and other integral features can be time consuming and complex.
In conventional assembly practices, close measurement and adjustment of sear-to-striker height and longitudinal positioning (typically either by replacement or by re-machining of parts) may be required due to variations of several assembly and manufacturing parameters within achievable tolerances. In particular, sear-to-striker height may be affected by the following parameters: the location of the striker with reference to the slide rails, the mating fit of the slide rails with respect to the slide locating rails, the location of the sear housing block relative to the slide locating rails, the sear pivot location within the sear housing block, and the height of the sear itself. Relative longitudinal positioning of the sear and striker within the frame may be affected by several of the above-mentioned parameters, as well as by the longitudinal position of the sear housing block within the frame.
Consequently, it has been conventional to fully assemble an auto-loading pistol and to then check sear-to-striker height, longitudinal positioning, and operation of the firing mechanism within the fully assembled pistol. Measurement of sear-to-striker height within an assembled pistol, and the occasional requirement to remove and replace or re-machine one or more assembled components in order to meet operational tolerances, however, lead to additional labor and expense in manufacturing of auto-loading pistols.
Accordingly, it has long been appreciated that it would be advantageous to better control sear-to-striker height and relative longitudinal positioning during assembly of auto-loading pistols.